How FRP Manhole Covers Reduce the Urban Heat Island Effect

The urban heat island (UHI) effect, where cities experience higher temperatures than surrounding rural areas, is driven by heat-absorbing materials like asphalt, concrete, and metal. Infrastructure components, including manhole covers, contribute to this phenomenon. Fiber-Reinforced Plastic FRP manhole cover offer a solution to mitigate the UHI effect, outperforming traditional metal covers. This blog explores how FRP helps cool urban environments.

Metal manhole covers, typically made of cast iron or steel, have high thermal conductivity, absorbing and retaining heat from sunlight and vehicle traffic. In summer, these covers can reach temperatures exceeding 140°F, radiating heat into the surrounding air and pavement. This exacerbates the UHI effect, increasing energy demands for cooling and worsening heat-related health risks. FRP, with its lower thermal conductivity, absorbs and transfers less heat, reducing localized temperature spikes.

FRP’s material composition, combining fiberglass and resin, inherently reflects more solar radiation than metal. Light-colored FRP covers, often used in urban settings, have higher albedo (reflectivity), bouncing sunlight back into the atmosphere rather than converting it to heat. A 2023 study by Arizona State University found that FRP covers in Phoenix were 15-20°F cooler than metal covers during peak summer hours, contributing to a measurable reduction in street-level air temperatures.

FRP's design flexibility enables additional UHI mitigation. To improve albedo, manufacturers can add reflected coatings or other materials to FRP coverings.  Some cities, like Miami, have adopted white or beige FRP covers, which reflect up to 70% of solar radiation compared to metal’s 30-40%. These covers not only stay cooler but also reduce heat transfer to underlying utilities, protecting infrastructure from thermal stress.

FRP’s lightweight nature indirectly supports UHI reduction. Installing or replacing metal covers requires heavy machinery, which generates heat and emissions. FRP covers, being up to 50% lighter, reduce the energy and time needed for installation, minimizing construction-related heat contributions. This aligns with urban sustainability goals, as seen in Los Angeles, where FRP adoption lowered installation emissions by 25%.

FRP’s durability also plays a role. Corroded metal covers often require frequent replacements, disrupting urban green spaces or cool pavement initiatives that combat UHI. FRP’s resistance to corrosion and chemical degradation ensures longer service life, reducing maintenance-related disturbances and preserving cooling strategies like tree canopies or permeable surfaces.

Real-world impacts are evident. In Dubai, a city prone to extreme heat, FRP covers in commercial districts lowered pavement temperatures by 10°F compared to metal-covered areas, easing pedestrian discomfort and reducing air conditioning loads. These benefits compound when FRP is integrated into broader UHI mitigation plans, such as reflective roofing or urban forestry.

In conclusion, FRP manhole covers reduce the urban heat island effect through lower thermal conductivity, higher reflectivity, and durable, low-maintenance designs. By staying cooler and supporting sustainable urban planning, FRP helps cities combat heat, improve livability, and reduce energy consumption.